The subject matter of the present invention pertains to an automatic well tool control system, and, more particularly, to multiple well tool control systems in a multi-valve well testing system including a means for automatically controlling the well tool control systems in response to kickoff stimulus which may include a sensing of bottom hole pressure or a sensing of the output of a strain gauge responsive to a set down weight of the well tool apparatus.
Multi-valve well testing tools of the prior art such as the well testing tools disclosed in U.S. Pat. No. 4,553,589 entitled "Full Bore Sampler Valve Apparatus", and in U.S. Pat. No. 4,576,234 entitled "Full Bore Sampler Valve", are typically mechanical in nature in that one valve disposed in the tool is mechanically linked to another valve disposed in the tool. If it is desired to open the one valve, an operator at the well surface, upon opening the one valve, must expect the other valve to be opened or closed as well since the two valves are mechanically linked together. Therefore, the operation of one valve is not independent of the operation of the other valve, and when one valve in the tool is opened, other valves disposed in the tool must be opened or closed in a specific predetermined sequence. A more recent and innovative apparatus for performing such well service operations, embodying pressure controlled valve devices, is shown in application Ser. No. 198,968, filed May 26, 1988, now U.S. Pat. No. 4,796,699, entitled "Well Tool Control System", assigned to the assignee of this invention, the disclosure of which is incorporated by reference into the specification of this application. In application Ser. No. 198,968 referenced hereinabove, a well testing tool is disclosed which is not totally mechanical in nature, rather, it embodies a microelectronics package and a set of solenoids responsive to the microelectronics package for opening or closing valve disposed in the tool. A set of solenoids embodied in the well tool of application Ser. No. 198,968 are energized by a microcontroller also embodied in the well tool, which microcontroller is responsive to an output signal from any type of sensor, such as a pressure transducer embodied in the tool that further responds to changes in downhole pressure created and initiated by an operator at the well surface. It is understood that the sensor may be responsive to other stimuli than downhole pressure. The solenoids, when energized in a first predetermined manner, open and close a set of pilot valves that permit a hydraulic fluid under pressure, stored in a high pressure chamber, to flow to another section of the tool housing where an axially movable mandrel is positioned. The fluid moves the mandrel from a first position to a second position thereby opening another valve in the tool (for example, a test valve or a reversing valve). When the set of solenoids are energized in a second predetermined manner, the hydraulic fluid, stored in the other section of the tool housing, where the movable mandrel is positioned, is allowed to drain from the housing to a separate dump chamber; as a result, the mandrel moves from the second position to the first position, thereby closing the other valve. In each case, the solenoids are responsive to an output signal from the microcontroller, which is, in turn, responsive to an output signal from the sensor, which is, in turn, responsive to changes in other input stimuli, such as changes in pressure in the well annulus. The change in input stimuli is created and initiated, each time, by the operator at the well surface. Therefore, an opening or closing of the other valve in the tool is responsive, each time, to a stimulus change signal (such as changes in downhole pressure) transmitted into the borehole by the operator at the well surface. However, application Ser. No. 198,968 discloses a well testing tool which includes one well tool control system for controlling the closure state of one valve. The above referenced well testing tool could also contain a plurality of well tool control systems for opening and closing a plurality of valves. In this case, two or more of the above well tool control systems and two or more corresponding valves would be embodied in a well testing tool. The two or more of such well tool control systems would open and close the two or more valves in response to predetermined input signals. An operator need only transmit into a borehole the two or more unique input signals corresponding to the two or more separate valves. As a result, the operation of one valve disposed in the tool would be performed totally independently of the operation of any other valve disposed in the tool. In the application Ser. No. 295,614, referenced above, a well testing system is disclosed including two or more well tool control systems interconnected respectively between two or more valves and a microcontroller. Whenever a valve must be opened or closed, the operator must transmit an input stimulus into the borehole, such as a pressure signal; the microcontroller generates its output signal in response to the input stimulus for energizing one of the control systems which then operates a particular valve. However, when it is desired to operate two or more valves in sequence, a separate input stimulus must be generated in the well testing system for each of the two or more valves. If suitable microcode were provided in the microcontroller, a plurality of openings and closings of the two or more valves in the tool could be accomplished automatically by the microcontroller upon execution of its own microcode in response to an initial kickoff stimulus generated in the well testing system, such as a sensing of a bottom hole pressure or a sensing of a strain gauge output sensitive to a set down weight of the well testing tool in the borehole.